The proposed research will examine the utility of applying clinical significance methodology to alcohol treatment outcome research. Analysis of alcohol treatment outcomes has typically focused on statistically significant mean differences from pre-to-post-treatment without determining meaningfulness of change for both individual participants and their clinical providers. In like manner, Project MATCH - a multi-site, collaborative study on patient-treatment matching - employed traditional statistical tests of significance primarily on consumption-related measures such as percent days abstinent (PDA) and drinks per drinking day (DDD). Neglected, were determinations of outcomes that go beyond these consumption measures to include those that tell clinicians more about individuals who were "successful" and "unsuccessful." This proposed study will examine clinical significance methodology as applied to Project MATCH. Project MATCH was a carefully designed, multi-site, clinical trial examining a series of hypotheses predicting which clients would do better in with three treatments - Cognitive Behavioral Therapy (CBT), Motivational enhancement Therapy (MET) or Twelve-Step Facilitation (TSF). A total of 1,726 subjects recruited from nine national sites representing either aftercare (n = 774) or outpatient (n = 952) settings were randomly assigned to receive one of the three treatments. There has been controversy over the clinical relevance of the results given the overall variability of main and matching findings and the magnitude of these effects. The present study provides an opportunity to rectify this deficiency by employing clinical significance classification procedures to the MATCH data set. Conventions will be established for determining clinical significance using alcohol outcome measures. Methods will enable us to classify participants based on whether individuals' functional status changes from pre-to-post-treatment and whether this change exceeds measurement error (i.e., is reliable). Efforts will be made to determine how the main and matching effects differ in time course and magnitude from the original findings when introducing clinical significance categorization procedures into the analysis. In addition, the role of individual and treatment characteristics that might discriminate on individual outcomes will be explored along with viability of and concordance with various alternative determinations of clinically significant classifications.